1. Field of the Invention
This invention relates generally to the operational control of a combination corrosion tester for actively testing what level of durability industrial materials or products exhibit because of natural phenomena under various environmental conditions.
2. Description of the Prior Art
A combination corrosion tester establishes specific environmental conditions inside one or a plurality of testing tanks in accordance with stipulated test conditions of a brine spray test, a dry test, a wet test, a low-temperature test, a dew test, an immersion test, a photoradiation test, etc., by providing a variety of controls. These tests are performed in accordance with a designated sequence for designated periods of time, and the tests are repeated a designated number of times in order to examine the durability of each testpiece. Recently, single-cycle tests, in which the test items are put in sequence and repeated, have proved to be insufficient for obtaining results close to those of complicated natural phenomena, and hence combinations of complicated cycles are now required. The requirements are not limited to combinations of cycles alone, but also necessitate testing methods in which set conditions of temperature and humidity of the same test item are changed during a cycle, and in which temperature control is effected in such a fashion that the temperature is gradually raised or reduced to target values with the passage of time, in addition to tests under a predetermined constant temperature.
In order to satisfy these requirements by conventional methods, a number of timers and temperature controllers corresponding to the test items must be added to the controller, and to assemble loops of repeated cycles, a number of preset counters corresponding to the number of loops must also be added to the apparatus. Furthermore, if the several levels of temperature must be set, the same number of temperature controllers as stages is necessary. From the programming point of view, a program controller is also necessary if control must be made while determining the gradients of temperature rises and falls. In addition to the problem that an enormous number of components are necessary, this results in the critical problem that if the circuitry is designed with a loop configuration governing the components, the apparatus can set and change only the selection and sequence of test items, the test time, the testing temperature, and the number of loops. It is almost impossible, in accordance with conventional methods, to freely change the loop configuration, and in order to accomplish such an object, the circuit must be redesigned from scratch, with the consequent necessity of changing wiring or connections.
One of the methods of providing the temperature control described above is a so-called "program control" which is employed when it is desired to gradually change the tempertaure with the passage of time, and which uses commercially-available cam controllers, gear controllers, photoelectric controllers or any of various other types of controllers. However, all of these are expensive, and can not be operated easily by just a key operation, although program changes are possible. Moreover, if a pattern which differs from one test item to another is required during a cycle, adjusters must be aligned for each pattern. In addition, the conventional system is not advantageous from the viewpoints of both space and cost.